1. Field of the Invention
This invention relates to two-compartment containers and in particular to collapsible containers used for holding two materials which can interact with each other.
2. Description of the Related Art
In U.S. Pat. No. 4,528,180, there is disclosed a dental preparation comprising two separately stored dental preparations which are used in combination on expulsion from their respective containers, for example a hydrogen peroxide gel which reacts when combined with a paste containing sodium bicarbonate, salt or other cleaning and polishing agents.
In U.S. Pat. No. 4,528,180 the two preparations are stored in two collapsible tubular housings arranged side-by-side with their outlet nozzles being interconnected, or merely being adjacent each other so that the materials mix on expulsion from the two compartments. Other two-compartment containers are shown in U.S. Pat. No. 5,318,203 and in WO 94/19251, in both of which the compartments are formed from separate circular tubes, each of which is distorted at one end to conform with the shape of a coupling having an outlet nozzle, the other ends being sealed into a "fish tail" closure by a common welded seam. In the above examples the tubes change their cross-sectional shape from a generally `D` shape at the couplings through an oval shape to a generally flat shape at the closure seam. Thus there is no consistent contact between the flexible tubes ensuring a consistency in the ratio of the two materials expelled from the compartments when the tubes are squeezed.
The present invention provides an improved two-compartment container.